393 Cerebral Oximetry Using the USIC Protocol Is a Reliable Tool for Indicating Selective Intraluminal Shunting During Carotid Endarterectomy

INTRODUCTION: Indication to selective shunting during carotid endarterectomy (CEA) is based on monitoring during the procedure. Cerebral oximetry (CO) using near-infrared spectroscopy (NIRS) is one of the monitoring tools but no clear cut off value for an intraluminal shunt insertion has been established. METHODS: 125 patients underwent CEA under LA and were monitored clinically through the whole procedure. The patients also underwent bilateral NIRS monitoring during the surgery. During the monitoring period, we first clamped the external carotid artery (ECA), and after a 1 minute delay followed by clipping the internal carotid artery (ICA). The decrease in the cerebral oximetry values was analyzed separately after selective ICA clipping (ÚstÍ Selective Internal carotid artery Clamping “USIC” protocol). The decision to use a shunt was based solely on clinical symptomatology but the NIRS data were recorded and analyzed. All patients underwent DWI before and after CEA. RESULTS: One hundred and six patients (85%) underwent CEA without clinical deterioration while 19 patients (15%) clinically deteriorated during surgery. The mean drop in the cerebral oximetry after selective ICA clamping in clinically stable patients was 6% while in patients with clinical deterioration the NIRS decreased by 15% (p < 0.05). When we set the cut-off value for selective shunting as a 10% decrease of the ipsilateral cerebral oximetry after selective ICA clamping, the sensitivity of the technique was 100% and the specificity 83%. CONCLUSIONS: Our study showed that a 10% decrease in the ipsilateral brain tissue oximetry after selective cross-clamping the ICA provides a reliable cut-off for selective shunting during CEA. More, bilateral NIRS monitoring allows differentiation between systemic or local events leading to brain hypoxia.